1. Technical Field
The present disclosure relates to a field emission cathode structure and a field emission display using the same.
2. Discussion of Related Art
Field emission displays (FEDs) are a novel, rapidly developing flat panel display technology. Compared to conventional displays, such as cathode-ray tube (CRT) and liquid crystal display (LCD), FEDs are superior in providing a wider viewing angle, lower energy consumption, smaller size, and higher quality.
Generally, FEDs can be roughly classified into diode and triode structures. Diode structures have a cathode electrode and an anode electrode, and are suitable for displaying characters, not suitable for displaying images. The diode structures require high voltage, produce relatively non-uniform electron emissions, and require relatively costly driving circuits. Triode structures were developed from diode structures by adding a gate electrode for controlling electron emission. Triode structures can emit electrons at relatively lower voltages.
Referring to FIGS. 11 and 12, a triode field emission cathode structure 10 is disclosed. The field emission cathode structure 10 includes an insulating substrate 12, a number of cathodes 14, a plurality of field emission units 11, a plurality of strip dielectric layers 16, and a plurality of grid electrodes 18. Specifically, the cathodes 14 fixed on the insulating substrate 12 are spaced from and parallel to each other. The field emission units 11 are positioned on the cathodes 14 and electrically connected to the cathodes 14. Each field emission unit 11 includes a plurality of field emitters. The dielectric layers 16 are mounted directly on the insulating substrate 12 and located at two flanks of the cathodes 14 to expose the field emission units 11. The grid electrodes 18 directly mounted on top surfaces of the dielectric layers 16. An axis of the grid electrode 18 is perpendicular to that of the cathodes 14.
When the field emission cathode structure 10 is operated, electrons are emitted from the field emitters. Part of the electrons hit the dielectric layers 16, and secondary electrons are emitted. After the secondary electrons are emitted, positive charges are accumulated on the dielectric layers 16; thus, the positive charges can change the potential around the dielectric layers 16. The change of the potential around the dielectric layers 16 results in increasing difficulty of controlling electron emission directions. Such that, images of a field emission display using the field emission structure 10 have low resolution.
What is needed, therefore, is a field emission cathode structure and a field emission display using the same with superior display resolution.